Date: Mon, 4 Nov 2002 11:56:33 -0800 (PST) From: Julian Elischer <julian@elischer.org> To: Agent Drek <drek@smashpow.net> Cc: Steve Francis <steve@expertcity.com>, "net@freebsd.org" <net@freebsd.org> Subject: Re: MTU problems ... Message-ID: <Pine.BSF.4.21.0211041155180.63544-100000@InterJet.elischer.org> In-Reply-To: <Pine.BSF.4.44.0211041259540.79976-100000@bang.smashpow.net>
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There is a program that intercepts tcp session negotiation and artificially reduces the negotiated MTU but I can't find it right now.. I think it was called mssd or something. On Mon, 4 Nov 2002, Agent Drek wrote: > On Mon, 4 Nov 2002, Steve Francis wrote: > > > Date: Mon, 04 Nov 2002 09:00:47 -0800 > > From: Steve Francis <steve@expertcity.com> > > To: Agent Drek <drek@smashpow.net> > > Cc: "net@freebsd.org" <net@freebsd.org> > > Subject: Re: MTU problems ... > > > > The problem below (which is still a problem in FreeBSD, but one that > > will be rarely encountered) was caused by a load balancer in front of > > the BSD boxes, that did not NAT part of the ICMP unreachable message > > payload to the BSD's address. (The ICMP includes part of the original > > datagram that caused the problem, and the load balancer did not > > translate the sequence numbers, I think.) Its still a BSD problem (I'd > > say) as if BSD hears the ICMP and reduces its MSS, it should not resend > > the original packet at a size > MSS. > > > > So this could be your issue if your ISP is forcing all your traffic > > through a proxy that does the same thing. > > > > A workaround would be disable PMTU-discovery. > > > > hi, > > I didn't notice the pr until now: > http://www.freebsd.org/cgi/query-pr.cgi?pr=42137 > > In my case the "load balancer" is something at the telco that is probably > aggregating a bunch of stuff at the dslam. Thus I can't really fix the > bad router, and there is no option of going somewhere else. > > I think I want something like: > > net.inet.tcp.stupid_router_in_front_of_me_mtu_hack->1 > > but that may not be what I need. Is it rude to send mail to that same > pr? should I try and harvest more info first? > > disabling path mtu discovery just cause the problem to happen faster > for me :( > > cheers, > > -- > Derek Marshall > > Smash and Pow Inc > 'digital plumber' > http://www.smashpow.net > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-net" in the body of the message > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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